<?php
 function test(){
     echo 123;
 }

 $b='test';

 $b();

 $arr=[
     ['name'=>'zhangsan','sex'=>'1','children'=>[
         ['name'=>'shanzhang','sex'=>2,'children'=>[
               ['name'=>'你说'],
               []
         ]
         ],
         [],
         [],
     ]
     ]
 ];

echo $arr[0]['children'][0]['children'][0]['name'];